Process of drying lumber



F. K. FISH, IR- PROCESS OF DRYING LUMBER. APPLICATION FILED MAR. 22' I917- BEYIEWED DEC. I3, I9I9.

Patented. Jan. 20, 1920.

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F. K. FISH, .IR. PBOIJESS 0F DRYING LUMBER.

APPLICATION FILED MAR.22,19I7- RENEWED DEC. 13.1919.

1,328,661, Patented Jan. 20, 1920.

3 SHEETS-SHEET 2.

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elftozncq F. K. FISH, JR. PROCESS 0f DRYING LUMBER.

' APPLICATION nuzu MAR.22. 191.1. neuzwso DEC. 13.1919. 1,328,661.

Patented Jan. 20,1920.

3 SHEETSSHEET 3- Hm I after u: 13

UNITED STATES PATENT OFFICE.

FREDERICK K. FISH, JR., OF NEW YORK, N. Y., ASSIGNOR TO LUMBER TIE & TIMBER VULCANIZING COMPANY, OF NEW YORK, N. Y.

rn'ocnss or DRYING LUMBER.

Specification of Letters Iatent.

Patented Jan. 20, 1920.

Application filed March 22, 1917, Serial No. 156,541. Renewed December 13, 1919. Serial No. 844,752.

To all whom it may concern:

Be it known that-I, FREDERICK K. Frsn, Jr., a citizen of the United States, residing at 2 Stone street. New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Processes of Drying Lumber. of which the following is a specification.

The present invention is based upon a proper recognition of the physical characteristics of the structure of wood and analogous fibrous or porous substances, the.

chemical constituency of their fluid content and the possibility of converting into an agency for preservation, certain of their contained elements, which, under natural conditions, would form the basis oftheir deterioration or destructiomthut refers more particularly to the treatment of the wood.

structurally, wood consists of a skeleton of cellulose intermingled with other organic substances, collectively designated as lignin, together with a minor proportion of mineral matter or ash. Lignin, while not fully understood chemically is closely allied to the cellulose element of the wood, and since it forms a part of the permanent structure of the wood, it may, for purposes of the present invention, be regarded identical with the cellulose.

To utilize the natural bases of resin, acetic acid and tannic acid, existing in wood, as preservatives-of the wood, it is necessary that they be dislodged from their cellular confinement, separated from their aqueous solvent or vehicle, converted by oxidation and properly distributed through or deposited upon the cellular and fibrous structure of the wood.

The invention relates to the process of ex tracting from the wood the fluid content thereof, or such substances as may be de veloped. therein during the operation of the process, and has for its object the drying of the wood proper and the collection therefrom of the fluids contained or developed therein during the process. Heretofore, it has been the practice-to collect these fluids by means of distillation requiring the en tire amount of fluids to be extracted by evaporation, and which requires a long and continuous supply of heat, which makes the process very expensive. While in the process herein set forth, a great portion of the liquid content of the wood is forced out of the Wood in an unevaporated state, which is due to the high temperature obtained by this process at the center of the wood piece, which forces the liquid content'through the surface thereof in its liquid form, and which method, in some cases, results in the obtaining of certain substances that are not obtained through evaporation.

I am aware that certain patents have been obtained for drying wood with free steam, and heat under vacuum. By thesemethods wood may be dried but requires such a length of time to accomplish an'ideal and uniform product under such methods as to make them uncommercial, from a lumberrnans viewpoint and cost such a large amount of money that such a process would not have any commercial value. If the time required to treat wood under such a process were reduced to a point where the methods would produce an amount of wood which would make it of interest to the lumber manufacturer, the heat in the sterilizer under the vacuum step would be of a degree that would cause the removal from the lumber of the preservatives of the wood, and therefore decrease very materially the value of the wood. In addition to which, the shrinkage in the wood would be great and excessive and the wood would be rendered brittle and where in close contact with the heating coils, would be discolored. In the method herein specified, the vacuum step is for such a short length of time that only the surface moisture is removed and the resin and gums are .distributed upon the fiber of thewood.

The release and conversion of these substances, especially the most important of them, namely, the volatile oils which, when oxidized, form resin, is accomplished, according to m invention, by racking the wood on a suitable truck or car, the individual pieces of the wood being spaced apart, the intervening spaces being filled with any substance which readily absorbs and radiates heat, such as gravel or metal; then placing thetruck load of wood in a sweat chamber and subjecting it to a moderately heated,

a saturated condition thereof for a period of time, the foregoing treatment having a tendency to open up the pores of the wood and in a measure soften the fibers thereof which renders it more receptive to the superheated water in the succeeding step; then introducing into the sterilizer super-heated water under pressure, preferably of about twenty pounds and of suflicient quantity to completely submerge the. wood, for a sufficient period, usually about one hour, to thoroughly open up the pores of the wood, dissolve its gummy sap matters that line its cellular tissues and put it into good physical condition to readily give up its aqueous content, without checking or other physical deterioration of the wood piece.

The wood naturally cools more slowly than the heat absorbing and radiating mate rial, and therefore the process of the cooling of the wood is retarded by the radiation of the heat from said material. The aqueous substances of. the wood, or some of them, are at a temperature well above their boiling point at the then existing pressure, which results in vaporization taking-place from the center of the wood piece outwardly,

and the internal pressure drives out of the.

wood the unvaporized liquid content. Any other suitable means for supplying additional heat to the wood may be employed for the heat radiating material which will admit of the control of the pressure and moisture of the vapor within the sterilizer. For instance, heat may be supplied to the sterilizer by steam circulated in steam coils. Proper saturation of the heating vapor is highly essential to the obtaining of said results. Variations of saturation are more or less controlled by the surface evaporation of the wood. This process results in the opening up and distending of the pores of the wood piece. The resultsof evaporation are now Withdrawn from the sterilizer and dry heat supplied therein by the circulation of steam through the heating coils until the desired temperature is obtained, to further evaporate any liquid content of the wood or procure such chemical reaction as may be desired or to liquefy or volatilize other ingredients of the wood. Next, the wood is su-b-' jected to what I term the equalizing step which consists in placing the wood in an equalizing chamber, which is'provided with heating pipes preferably located at the bottom.= This equalizing chamber is further provided with tracks for convenient intro: duction of the charge of lumber, and its walls are preferably constructed so as to have a high coefiicient of heat insulation for the sake of economy of operation. Finally, the wood is placed in a cooling chamber, said chamber preferably having insulated walls and the wood therein subjected to a moderately. heated, moist atmosphere until the center of the Wood piece and the surrounding atmosphere are harmonized. The wood will now be thoroughly dried without removing the values of its sap; the latter will be converted especially as to its-volatile oils, into resin; this resin having permeated the entire cellular structure of the wood, while the moisture was still present and the pores opened up and temperature high, will have precipitated upon or surrounded the cell walls or fibers now that the moisture has departed. Thus, the wood has been renderedhomogeneous throughout, and so treated by its contained preservatives as to lend to it distinctive characteristics that make. it a new article of manufacture, that is to say, the wood subjected to the foregoing treatment will be indurated, sterilized and rendered less hygroscopic and corres' ondingly immune from spores of fermentation or the like. And all these conditions are attained without checking, warping, case hardening or other deterioration of the acteristics of the wood. 1

By way of teaching the invention more in detail. one approved method of practising the same will be described with reference to the accompanying drawings, 1n which .Figure I is a vertical longitudinal section of a container, suitable for carrying Fig. V is a section on the line 5 -5,

Fig. IV.

Fig. VI is a plan view showing the various containers for the wood with the Connect ing means thereof for carrying out the several steps of the process. f

1 represents a sterilizer of construction suitable'for containing water at a temperature and under pressure considerably above the boiling point. 2 and 3 are uprights for firmly holding the lumber in proper position while being treated. It is also provided with heating coils 4. by which the tempera ture of the atmosphere. steam or water within the sterilizer may be heated to the desired degree: and with coils 5 which may be perforated for the purpose of supplying free steam within the sterilizer when desired. To equip the sterilizer 1 for conveniently developing the several conditions incident to the difl'erent steps of the process, it is provided with an exhaust pipe 6 leading to a vacuum pump 7 with an interposed condenser 8; a water supply pipe 9 that com;

municates with an'uptake pipe 10 leading from an elevated water supplv tank and physical charbe withdrawn, and for the sake of economy,

returned to the elevated tank for re-use.

Water supplied through pipes 9 and- 10 to the sterilizer 1 will preferably be previously heated and the coils 4 relied upon for maintaining its heat or raising it to the proper degree. The pipes (i. 9 and 10,.as well as the connections with the return pump for the water. are provided with suitable valves to open and close them appropriately to the several steps ofthe process. 12 represents tracks to receive the car or truck 11 on which the lumber is loaded for intro uction into the sterilizer.

Referring to Figs. IV and V, 13 represents the equalizing chamber which preferably provided with heating pipes 14 preferably located at the bottom. This equalizing chamber further provided with tracks 15 for convenient introduction of the charge of lumber, and its walls are preferably constructed so as to have a high co-eflicient of heat insulation for the sake of economy in operation, In Fig. VI 16 represents the boiler; 17, the .sweat chamber; 1, the sterilizer; 1 8, represen s tracks extending through the sweat chamber and equalizer for the convenient introduction therethrough of a car-load of lumber; 19 is the transfer platform which is provided with track, 20, for the reception of a car of lumber; 2-1 is a track for the convenient introduction of lumber into any one of the equalizing chambers, 13; 22 are cooling chambers; 15 are tracks extending through they equalizing chambers and cooling chambers for the introduction therethrough of a car of lumber.

From the foregoing. it will be seen that the first essential condition to be produced is the thorough softening and opening up of the wood structure. and the dissolving of its gummy sap matters and freeing them from their confinement, so that they can be distributed through the wood structure. The equalizing step thoroughly and finally sets the resin throughout the wood )iece, the resin having been equally distri uted throughout the wood piece and permeated the cellular structure of the wood, been deposited in the formof a shellac upon the cell vwalls thereof and been diffused through the individual fibers thereof. Thus the wood will be dried and preserved by its own contained resinous properties, and this condition will have been attained without checking, warping or case hardening of the wood piece.

I claim 1. The processof extracting the fluid content of wood and substances contained therein, which consists in first sweating the wood in a moderately heated, moist atmosphere; then subjecting it to a body of saturated steam under pressure, said steam being heated to the boiling point of the fluid content and substances of the wood which it is desired to extract; then slib'merging the wood in super-heated water under pressure until its structure is softened, its pores are opened up and its gummy sap matters dissolved; then removing the water from the presence of the wood; then surrounding the wood with a body of dry heat until suflicient internal vaporization has-been produced to extract from the wood its fluid content and substances contained therein;

.i'nally surrounding the wood, with a modtent of .wood and substances containe therein, consisting of associating the wood with a heat absorbent; then-subjecting the whole to a sweating; then surrounding the whole with a body of steam; then submerging it in super-heated water until its struc-' ture is softened, its pores opened up and its gummy sap matters dissolved; then removing the super-heated water from the presence of the wood; then surrounding it with; a body of dry heat; finally subjecting it to a moderately heated, moist atmosphere after sufficient vaporization'of its fluid content and substances contained therein has taken place. i

3. The process of extracting the fluid content of wood and substances contained therein, consisting of first placing the wood ina sweat chamber and creating in said chamber a moderately heated. moist atmosphere; then submerging the wood in superheated water under pressure until its structure is softened, its pores opened up and its gummy sap matters dissolved; then removing the super-heated water from the presence of the wood; then subjecting the wood to a body of dry heat at high temperature; finally cooling in the presence. of a mod erately. heated, moist atmosphere at atmospheric pressure.

4. The process of extracting the fluid content of wood and substances contained therein by first assembling the wood with a heat absorbing and radiating medium; then subjecting the whole to a moderately heated, moist atmosphere; then surrounding it with a body of saturated steam under pressure; said steam being heated to the boiling point of the substances contained therein which it is desired to extract; then submerging the wood in super-heated water until its structure is softened. its pores opened up and its gummy sap matters dissolved: then removing the super-heated water from the presence of the wood; then subjecting it to dry heat; finally surrounding the Wood with a moderately heated, moist atmosphereuntil the temperature at the center of the wood piece and that of the surrounding atmosphere have been harmonized.

5. The process of extracting the fluid content and substances contained therein from wood, which consists in co-mingling with the wood a medium that more readily absorbs and radiates heat, and then subjecting the Whole to a sweating process at a moderate temperature; then subjecting it to the action of saturated steam in a hermetically closed sterilizer under pressure and at a temperature equal to the boiling point of the fluid content of wood which it is desired to extract therefrom; then submerging the wood in superheated water until its structure is softened, its pores opened up and its gummy sap matters dissolved; then removing the super-heated Water from the presence of the Wood; then subjecting it to a body of dry heat; finally cooling in a moderately heated, moist atmosphere.

6. The process of extracting the fluid contemperature equal to the boiling point of.

the fluid content which it is desired to extract therefrom; then reducing the pressure and temperature of the steam; then submerging the wood in super-heated Water until its structure is softened, its pores opened up and its gummy sap matters dissolved; then remoring the superheated water from the presence of the wood; then subjecting the wood to a body of dry heat; finally cooling in the presence of a moderately heated, moist atmosphere.

In testimony whereof I affiX my signature.

FREDERICK K. FISH, JR. 

